JPH04136404A - Valve timing control device - Google Patents

Abstract

PURPOSE:To make the timing of one of both banks identical to the timing of the other bank so as to restrain rotational fluctuation and torque fluctuation of an engine by detecting a shape changing amount due to secular change of a timing belt or a chain so as to correct the control amount of a valve timing variable mechanism on the basis of the result. CONSTITUTION:In an ECU 23 during operation of an engine, a phase difference between a crank shaft 2 and a cam shaft 6 is found out, and compared with a normal phase difference, so that the difference thereof is rendered a present phase deviation. This phase deviation is added to a prior phase deviation addition value so as to obtain a new phase deviation addition value thetaN, and when addition times N reaches a prescribed value alpha, the phase deviation addition value thetaN is divided by the addition times N so that the result of the division is rendered an average phase deviation thetaRH serving as a correction amount in the cam shaft 6 of a right bank 4. On the other hand, the average phase deviation thetaRH is multiplied by an adaptation value K1 so as to obtain an average phase deviation thetaLH in the cam shaft 5 of a left bank 3. The average phase deviation thetaRH is added to real control value so as to obtain a final control value so that a valve timing may be corrected by cam pulley assemblies 7, 8.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a valve timing control device that controls the operation timing of intake valves and exhaust valves during engine operation. This invention relates to a valve timing control device for a multi-cylinder engine which is arranged in two banks.

[Prior Art] Conventionally, as this type of valve timing control device, for example, Japanese Utility Model Application Publication No. 61-145806 discloses a multi-cylinder V-type engine in which two left and right banks are arranged in a V-shape around a crankshaft. , it is disclosed that a variable valve timing mechanism (VVT) is provided for the camshaft of each bank. In such a valve timing control device, the camshaft of each bank is drivingly connected to the crankshaft via a timing belt or chain. Additionally, by controlling each VVT at the same timing during engine operation, the camshafts of each bank can be controlled at the same rotational phase, making it possible to control the operation timing of the intake and exhaust valves of each bank at the same phase. .

[Problems to be Solved by the Invention] However, in the conventional valve timing control device,
- There was a problem that the timing belt or chain drivingly connecting each camshaft to the crankshaft stretched over time. Then, by extending the timing belt or chain, VV on each left and right bank is increased.
A difference occurs in the timing of T operation. For example, in a 6-cylinder V-type engine, if a 2° CA deviation occurs in the left bank, a 4° CA deviation occurs in the right bank. As a result, a rotational phase difference occurs between the camshaft and crankshaft of each bank, resulting in a difference in valve timing between each bank. As a result, the required ignition timing and required injection amount will differ between each bank.
Engine rotational fluctuations and torque fluctuations increased, which could lead to deterioration in drivability and exhaust gas.

This invention was made in view of the above-mentioned circumstances, and its purpose is to eliminate valve timing discrepancies between two banks, thereby suppressing engine torque fluctuations and improving drivability. An object of the present invention is to provide a valve timing control device capable of suppressing deterioration of exhaust gas.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides banks in which each cylinder of a multi-cylinder engine is arranged in two positions around the crankshaft, and one timing belt or chain hung to drive and connect the camshaft provided in each bank to the crankshaft; and a variable valve timing mechanism provided to vary the valve timing in each bank; In a valve timing control device comprising a control means for driving and controlling a variable valve timing mechanism according to the operating state of an engine so as to control valve timing in each bank in the same phase, the amount of change in shape due to change in timing belt or chain over time. control means for controlling the variable valve timing mechanism based on the detected amount of shape change in order to correct the deviation in valve timing between each bank caused by the change in timing belt or chain over time; and control amount correction means for correcting the amount.

[Operation] According to the configuration of the invention described above, the camshaft provided in each bank of the multi-cylinder engine is rotationally driven via the timing belt or chain suspended between the camshaft and the crankshaft. The control means controls the valve timing of each bank in the same phase (and controls the variable valve timing mechanism according to the operating state of the engine).

At this time, the control amount correction means corrects the control amount of the variable valve timing mechanism by the control means based on the amount of change in shape due to the change over time detected by the change over time detection means.

This corrects valve timing deviations between banks that occur due to aging (elongation, etc.) of the timing belt or chain.

[First Embodiment] Hereinafter, a first embodiment embodying the present invention will be described in detail based on the drawings.

FIG. 1 shows a schematic configuration diagram of a gasoline engine to which the valve timing control device of the present invention is applied.

Here, the description of the operational control of the engine 1 will be omitted since it is assumed that well-known control is performed, and only the valve timing control will be described.

In this embodiment, each cylinder of the multi-cylinder V-type engine I is arranged at two positions on the left and right with the crankshaft 2 as the center, forming left and right banks 3 and 4, respectively. At one end of the camshafts 5 and 6 provided in each bank 3 and 4, there is a cam pulley that changes the opening and closing timing (valve timing) of intake valves and exhaust valves (not shown) that are driven to open and close by the camshafts 5 and 4. Rashii 7,8
are provided for each.

Each of the cam pulleys 7, 8 has a built-in actuator (not shown) driven by hydraulic pressure. The configurations of these cam pulleys 7 and 8 are already well known, so a detailed explanation will be omitted here. Further, a hydraulic circuit 9 is provided for regulating the supply of hydraulic pressure to each cam pulley 7.8. This hydraulic circuit 9 includes oil passages 10 and 11 leading to the respective cam pulleys 7 and 8, and a tank I2.
Hydraulic pump 13 and electromagnetic valve 14 for pumping hydraulic oil
It is composed of a pump unit 15 consisting of: In this way, the cam pulley 7° 8 and the hydraulic circuit 9 constitute a variable valve timing mechanism (VVT) for varying the valve timing of each bank 3, 4. The cam pulley lashes 7 and 8 are driven by hydraulic pressure, so that the cam pulley lashes 7 and 8 are driven by hydraulic pressure.
8 and each camshaft 5.6 to adjust the valve timing. In addition, pump unit 1
5 can also be used in common with the oil pump installed in the engine 1 in advance.

A crank pulley 6 is fixed to one end of the crankshaft 2. A timing belt 17 is hung between each of the cam pulleys 7 and 8 and the crank pulley 16, and each of the camshafts 5 and 6 is drivingly connected to the crankshaft 2. The engine 1 is also provided with an idler 18, 19 and a tension boob 920 for applying a required tension to the timing belt 17.

The right bank 4 is provided with a cam rotation speed sensor 21 that detects the rotational phase of the camshaft 6. Further, an engine rotation speed sensor 22 is provided to detect the rotation speed (engine rotation speed) of the engine 1 rotating in the same phase as the crankshaft 2.

The aforementioned cam rotation speed sensor 21, engine rotation speed sensor 22, etc. are connected to the input side of an electronic control unit (ECU) 23 that constitutes a control means and a control amount correction means. Furthermore, the above-mentioned pump unit 15 is installed on the output side of the ECU 23.
The electromagnetic valve 14 and the like are connected to it. This ECU23
is a central processing unit (CPU), a read-only memory (R
It is configured as a logic operation circuit consisting of a memory (RAM), which can be called and rewritten (RAM), etc. and,
The ECU 23 suitably performs duty control on the electromagnetic valve 14 in accordance with the operating state of the engine 1, that is, based on the detected values of the sensors 21 and 22, so as to control the valve timing in each bank 3 and 4 in the same phase.

Moreover, the cam rotation speed sensor 21 and the engine rotation speed sensor 2
Reference numeral 2 constitutes a temporal change detecting means for detecting the F extension J as the amount of change in shape of the timing belt 17 due to temporal change. In order to correct the valve timing deviation between the banks 3 and 4 caused by the extension of the timing belt 17, the ECU 23 uses the sensors 21 and 2.
The control amount of the electromagnetic valve 14 is corrected based on the detected value of No. 2.

Next, the operation of the valve timing control device configured as described above will be explained according to the flowchart shown in FIG. Incidentally, this flowchart shows a correction routine among the routines executed by the ECU 23 for correcting the phase shift between each camshaft 5.6 and the crankshaft 2 due to the extension of the timing belt 17. . This correction routine is executed by the ECU 23 with regular interruptions at predetermined times.

When the process moves to this routine, first step 101
In the step, it is determined whether the valve timing is in the base timing state. That is, it is determined whether or not the electromagnetic valve 14 is closed and control hydraulic pressure is not being supplied to each of the cam pulleys 7 and 8.

If it is not in the base timing state, the subsequent processing is temporarily terminated. If the state is the base timing state, the process moves to step 102.

In step 102, based on the detected values of the cam rotation speed sensor 21 and the engine rotation speed sensor 22, as shown in the time chart in FIG. Find the phase difference "θ1-θ2" with the rotational phase θ1, compare the phase difference "θl-θ2" with the normal phase difference θ0,
The difference is defined as the current phase deviation θN1.

Next, in step 103, the current phase deviation θN1
is added to the previous phase deviation addition value θN to obtain a new phase deviation addition value θN.

Subsequently, in step 104, "1" is newly added to the number N of additions of the phase deviation θN1 up to the previous time in step 103, and the result is set as the current number N of additions.

Then, in step 105, it is determined whether the number of additions N has reached a predetermined value α. Here, if the number of additions N has not reached the predetermined value α, the subsequent processing is temporarily terminated. Also, when the number of additions N reaches the predetermined value α,
The process moves to step 106.

In step 106, the phase deviation addition value θN is divided by the number of additions N, and the result is set as the average phase deviation θRH as the correction amount for the camshaft 6 of the right bank 4.

Further, in step 107, the average phase deviation θRH of the right bank 4 is multiplied by 1, and the result is set as the average phase deviation θLH as the correction amount for the camshaft 5 of the left bank 3.

In this embodiment, a cam rotation speed sensor 21 is provided only on the cam pulley arasse 8 of the right bank 4. Also, the fourth
As shown in the graph of the figure, it is known that there is a certain proportional relationship between the valve timing deviations in the left and right banks 3 and 4 with respect to the length of the timing belt 17.

Therefore, in this step 107, the cam rotation speed sensor 2
Based on the average phase deviation θRH obtained based on the detected values of the camshaft 1 and the engine rotation speed sensor 22, a calculation is performed to determine the average phase deviation θLH of the camshaft 5 of the left bank 3. Here, the above-mentioned adaptation value Kl is a value determined by the design length of the timing belt 17 according to its layout (0<Kl≦1).

Then, in step 108, the actual control value θVV
The average phase deviation θRH is added to T to obtain the final control value θVVTr in the right bank 4, and the control value θVVTr
The solenoid valve 14 is duty-controlled according to the following. As a result, when the cam pulley arashi 8 in the right bank 4 is driven, the phase difference between the camshaft 6 and the crankshaft 2 caused by the extension of the timing belt 17 is corrected, and the valve timing in the right bank 4 is corrected. is corrected at the appropriate timing.

Furthermore, in step 109, the actual control value θVVT
The average phase deviation θLH is added to the final control value θVVTl for the left bank 3, and the electromagnetic valve 14 is duty-controlled in accordance with the control value θVVTI, and the subsequent processing is temporarily terminated.

As a result, when the cam pulley arashi 7 in the left bank 3 is driven, the phase difference between the camshaft 5 and the crankshaft 2 caused by the extension of the timing belt 17 is corrected, and the valve timing in the left bank 3 is corrected. is corrected at the appropriate timing.

As described above, according to the valve timing control device of this embodiment, the phase difference between the camshafts 5 and 6 of the left and right banks 3 and 4 and the crankshaft 2 caused by the stretching of the timing belt 17 is reduced. The valve timings in each bank 3 and 4 are respectively corrected to appropriate timings.

Therefore, even if the timing belt 17 is stretched due to changes over time, the valve timing deviation between the left and right banks 3 and 4 can be corrected and eliminated. As a result, it is possible to suppress fluctuations in the rotational speed and torque of the engine l caused by valve timing deviations, and to prevent deterioration of drivability and exhaust gas.

[Second Embodiment] Next, a second embodiment embodying the present invention will be described with reference to the drawings.

FIG. 5 shows a schematic configuration diagram of a gasoline engine to which the valve timing control device of the present invention is applied.

Also here, the description of the operational control of the engine 1 will be omitted since it is assumed that well-known control is performed, and only the valve timing control will be described. Incidentally, the configuration of the valve timing control device of this embodiment is basically the above-mentioned first
Since this embodiment is almost the same as that of the embodiment, a detailed explanation will be omitted, and only the different points will be explained.

As shown in FIG. 5, in this embodiment, each of the left and right banks 3
, 4 is a simple cam pulley 2 with no built-in actuator for hydraulic control at one end of the camshafts 5 and 6 provided in the camshafts 5 and 6.
6 and 27 are fixed.

On the other hand, at one end of the crankshaft 2 is a crank pulley 2 which has a built-in actuator for hydraulic control.
8 is provided. Also, crank pulley 28
The oil passage 29 communicating with the pump unit 15 and the pump unit 15 constitute a hydraulic circuit 30 that adjusts the supply of hydraulic pressure to the crank pulley 28. That is, in this embodiment, the crankshaft 2 is provided with a crank pulley 28 having a built-in actuator for hydraulic control, and the rotations of the camshafts 5 and 6 of the left and right banks 3 and 4 are simultaneously controlled in phase.

Next, the operation of the valve timing control device configured as described above will be explained according to the flowchart shown in FIG. Incidentally, this flowchart shows a correction routine among the routines executed by the ECU 23 for correcting the phase shift between each camshaft 5.6 and the crankshaft 2 due to the extension of the timing belt 17.

This correction routine is executed by the ECU 23 with regular interruptions at predetermined times.

When the process moves to this routine, first step 201
In the step, it is determined whether the valve timing is in the base timing state. That is, it is determined whether or not the electromagnetic valve 14 is closed and no control hydraulic pressure is being supplied to the crank pulley latch 28.

If it is not in the base timing state, the subsequent processing is temporarily terminated. If the state is the base timing state, the process moves to step 202.

In step 202, the phase difference "θl" between the rotational phase θ2 of the crankshaft 2 and the rotational phase θl of the camshaft 6 in the current processing cycle is determined based on the detected values of the cam rotational speed sensor 21 and the engine rotational speed sensor 22. −θ
2J, and its phase difference "θ1-θ2" and normal phase difference θ
0, and the difference is set as the current phase deviation θN1.

Next, in step 203, the current phase deviation θN1
is added to the previous phase deviation addition value θN to obtain a new phase deviation addition value θN.

Subsequently, in step 204, IJ is newly added to the number of additions N of the phase deviation θN1 up to the previous time in step 203, and the current number of additions N is set.

Then, in step 205, it is determined whether the number of additions N has reached a predetermined value α. Here, if the number of additions N has not reached the predetermined value α, the subsequent processing is temporarily terminated. Also, when the number of additions N reaches the predetermined value α,
The process moves to step 206.

In step 206, the phase deviation addition value θN is divided by the number of additions N, the adapted value is multiplied by 2, and the result is used as a common corrected phase deviation for the camshafts 5 and 6 of each left and right bank 3.4. Let it be θAD.

Here, the above-mentioned adaptation value 2 is a value determined by the design length according to the layout of the timing belt 17 (0<
K2≦1). FIG. 7 is a graph showing the relationship between the valve timing deviation of each bank 3 and 4 with respect to the length of the timing belt 17. In this embodiment, in order to simultaneously correct the valve timing deviations of the left and right banks 3 and 4, the phase deviation addition value θN is divided by the number of additions N, and the result is multiplied by 2 by the adaptive value. As shown by the solid line in FIG. 7, an intermediate value of the valve timing deviation between the left and right banks 3 and 4 is determined.

Then, in step 207, the actual control value θVV
By adding the corrected phase deviation θAD to T, the left and right banks 3 and 4 are
Let the final control value θVVTa be the final control value θVVTa, and the control value θ
Duty-controls the electromagnetic valve 14 according to VVTa,
The subsequent processing is temporarily terminated. As a result, when the crank pulley lag 28 of the crankshaft 2 is driven, the phase difference between the camshafts 5.6 of the left and right banks 3, 4 and the crankshaft 2 caused by the extension of the timing belt 17 is reduced. are simultaneously corrected to decrease.

As described above, according to the valve timing control device of this embodiment, the phase difference between the camshafts 5 and 6 of the left and right banks 3 and 4 and the crankshaft 2 caused by the extension of the timing belt 17 is reduced. They are each corrected so that the valve timing deviations in each bank 3 and 4 are corrected to be small.

Therefore, even if the timing belt 17 is stretched due to changes over time, it is possible to correct the valve timing deviation in each of the left and right banks 3 and 4 and make the effect of the deviation the same. As a result, it is possible to suppress rotational fluctuations and torque fluctuations of the engine l caused by deviations in valve timing, and it is possible to prevent deterioration of drivability and exhaust gas.

The present invention is not limited to the above-mentioned embodiments, and may be implemented as follows by appropriately changing a part of the structure without departing from the spirit of the invention.

(1) In the first embodiment, the cam rotation speed sensor 21 was provided only on the right bank 4, and the detected value was used as the input value of the ECU 23, but a cam rotation speed sensor was installed on each of the cam pulleys of the left and right banks. It may also be provided as an input value to the ECU.

(2) In each of the embodiments described above, the elongation of the timing belt 17 is corrected, but the elongation of the chain may be corrected.

(3) In each of the above embodiments, a multi-cylinder V-type engine is used, but a multi-cylinder horizontally opposed engine may be used.

[Effects of the Invention] As detailed above, according to the present invention, the amount of change in shape due to changes in the timing belt or chain over time is detected, and the control amount of the variable valve timing mechanism is corrected based on the amount of change in shape. This makes it possible to correct valve timing discrepancies between the two banks that occur due to changes in the timing belt or chain over time, making the valve timing in both banks the same, which in turn reduces engine rotational fluctuations and torque. It has the excellent effect of suppressing fluctuations and preventing deterioration of drivability and exhaust gas.

[Brief explanation of drawings]

1 to 4 are drawings relating to a first embodiment embodying the present invention, in which FIG. 1 is a schematic configuration diagram showing a valve timing control device, and FIG. 2 explains the valve timing control. 3 is a flowchart, FIG. 3 is a time chart explaining the relationship between the crankshaft rotational phase and the camshaft rotational phase, and FIG. 4 is a graph explaining the relationship between the valve timing deviation and the extension of the timing belt. 5 to 7 are drawings relating to a second embodiment embodying the present invention, in which FIG. 5 is a schematic configuration diagram showing a valve timing control device, and FIG. 6 explains the valve timing control. The flowchart, FIG. 7, is a graph illustrating the relationship between valve timing deviation and timing belt elongation. In the figure, ■ is the engine, 2 is the crankshaft, 3 is the left bank, 4 is the right bank, 5 and 6 are the camshafts, 7 and 8 are the cam pulley lashes, 9 is the hydraulic circuit (7 to 9 are variable valve timing mechanisms) ), 17 is a timing belt, 21 is a cam rotation speed sensor, 22 is an engine rotation speed sensor (21°22 is a temporal change detection means), 23 is a control means and a control amount correction means E that constitutes
CU, 28 is a crank pulley arrangement, and 30 is a hydraulic circuit (28 and 30 constitute a variable valve timing mechanism). Patent applicant Toyota Motor Corporation Agent
Patent Attorney On 1) Hironobu (and 1 other person) Diagram: Timing belt extension number? Diagram Timing belt extension diagram

Claims (1)

[Scope of Claims] 1. Each bank in which each cylinder of a multi-cylinder engine is arranged in two positions with a crankshaft as the center, and a camshaft provided in each bank is drivingly connected to the crankshaft. a timing belt or chain hung thereon to control the valve timing; a variable valve timing mechanism provided to vary the valve timing in each bank; and a variable valve timing mechanism provided to control the valve timing in each bank in the same phase. A valve timing control device comprising: a control means for driving and controlling the variable valve timing mechanism according to the operating state of the engine; Correcting the control amount of the variable valve timing mechanism by the control means based on the detected amount of shape change in order to correct the deviation in valve timing between the banks caused by aging of the timing belt or the chain. A valve timing control device comprising a control amount correction means.